Who IS Jeremy Pena- Two Part Series

He has been out injured and he has been missed. Jeremy Pena is scheduled to be in the lineup today and we welcome him back in LarryTheGM style. This is the first followup of probably several where we will boldly project who we think Jeremy Pena really is as an MLB Player. This will be a two part series.


Part 1- We will revisit what Clint the Scout and I wrote about in December. We will review what we saw and what we projected then. Clint will describe WHY he saw what he did and deep dive into the early data.

Part 2- We will project Jeremy Pena forward. After 30 MLB games we will do the impossible- tell you who we think Jeremy Pena can really be. We will also add a word of warning so be prepared.



Part 1- What WE told you in December and WHY


Before reading on, Stop. Read what Clint and I wrote in December. Let me include the key paragraph summarizing our prediction for Pena in December.


My official prediction for Pena would be what Clint is seeing that leads to more power IS REAL and that the best projection is probably and average of the "LGM" and "FG stm" (Fangraph's Steamer).


My best projection for Pena is

BB%- 5.5%. (need to focus on plate discipline)

K%- 27.1% (cut the strikeouts down!)

OBP- 0.305 (get more walks- a theme?)

Slug- 0.438 (Pretty good! 2021 Astros team average 0.444, 2021 MLB average 0.411)

OPS- 0.743 (Above Average! 2021 Astros team average 0.783, 2021 MLB average 0.728)


If Pena lives up to THIS projection as an above average hitter with his strong defense, there would be no reason to sign a high priced Free Agent SS.


In the article in December I described my methodology of projecting Pena based on a population factor to his combined AAA AND his winter league stats. My official prediction was the average of this calculation on the Steamer projection because quite frankly my calculation was significantly better than anything anyone was predicting for Pena.


So let's put the predictions and the reality so far next to each other AND where those predictions NOW predict for Pena.



What did we get right or righter?

  • We said there would be more power- Clint told you why and the Calculation predicted it

  • We thought he would get on base more (hit better) than the Steamer model said.

What did we get wrong?

  • I was predicting and quite concerned he would strike out more than he has. Understanding what Clint will describe below may indicated adjustments that MLB teams may bake to increase Pena's strikeout rate.

Where has Pena been better than either of us said?

  • Early on, Pena has been even better at delivering the power than I calculated and significantly more than I was willing to predict.

  • Pena has walked more. This is a very important thing to monitor.

You might also notice that the CURRENT predictions for Pena for the rest of the season basically all narrow in pretty closely from a OBP/ SLUG/ OPS prediction to what I calculated in December. You are not wasting your time here. You are becoming a smarter sports fan.


Clint Tried to tell us by having us LOOK at Pena's swing that the power in his brief run in AAA was real. He was right- at least so far.


Clint now gives us another deep dive into what Pena's early data tells us about him. I suggest you listen.


Jeremy Peña and the Predicted Power- by Clint the Scout


First, let’s give Jeremy Peña a huge ovation for his performance so far this season. The 24-year-old rookie stepped into the starting shortstop role of a perennial championship contender, and has flashed power, speed, and defense. I’d like to say I’m surprised, but I saw this back in December when we first broke down Peña as the new shortstop.

The entire situation was quite dramatic. The Astros Front Office took a very strong stance on filling the shortstop position, or in my eyes they did. It was between resigning Carlos Correa to a contract fitting their terms or starting Peña. The data the Astros Front Office had to crunch, and the confidence in their analysis led to what we see today. It’s a very bold statement to overlook Trevor Story or another veteran for a young man who essentially skipped Triple-A ball (29 games and 113 plate appearances at AAA).


Before I dive in, I want to credit Baseball Savant and Fangraphs for the data I use in this article.

To the left is Baseball Savant’s MLB Percentile Rankings for Peña. It tells us all we need to know regarding his first 111 MLB plate appearances. We have seen power from the left field wall to straight-away center field. We have seen his speed on the bases and the ability to generate walks in some high-leverage situations. This speaks to his baseball IQ and maturity as a young ballplayer.

So, the power we have seen is nothing short of amazing considering the sample sizes. The work he continues to do to route the barrel of the bat efficiently gives him the necessary speed to drive baseballs out of the park. If you’re watching, notice how he waggles the barrel back in a flattening motion. This is to help generate the desired plane through the strike zone. In the article profiling Peña, I noted the extent to which the barrel travelled was far longer than it does now. Add this with the ability to flatten the plane of the bat throughout impact, and you generate a much more stable force into the baseball. It’s centrifugal force, the act of movement in the handle of the bat would then impose movement on the outer circle which the barrel travels. Peña has improved and continues to work to get the barrel much more in front and in a position to deliver directly into the baseball on a flatter plane. Obviously, folks will say, this doesn’t translate to launch angle, and you’re right. However, if the centrifugal force of the hands moving the barrel from behind your head to out in front and then into the impact zone, the barrel dips. It’s physics. The quickest, most efficient way to generate power is to move the barrel through impact on a flat, direct plane. I believe Peña is focused on this and it’s giving him the power he’s seeking.


The proof is in the pudding. Check out the table below:

Why those metrics? Because they all play a part in one another’s calculation. In my opinion, power isn’t just about home runs. It’s about maximizing the velocity of the ball off the bat. The design of a ball, a sphere, contacting a cylindrical object, only make the task of generate solid contact with power a very difficult goal. The margin between hits and out is so thin. Peña is showing he can apply that power to balls batted. He’s able to generate hits when the ball is in play and hits them hard when he does.


However, he does tend to swing and miss more than most, and strike outs a lot more than you’d want. Of course, I’m being picky, right? His next level for growth is developing a better approach to off-speed pitches and breaking balls. He’s shown ability to hit them, and even with power. However, the chase and whiff percentage suggest he’s still learning how to attack those pitches. Obviously, most hitters are not as proficient when behind in the count, but Peña produces a 50% whiff rate on breaking balls. This is easily attributed to his aggressive approach or going after pitches that are truly out of the zone. Pitchers tend to burn pitches by dropping them in the dirt or starting them so far off the plate that an aggressive fastball hitter like Peña is too far into his timing to jump on the velocity, he’s overcommitted. This doesn’t mean when he’s ahead in the count, that he’s mashing breaking balls. He currently holds a 38% whiff rate on breaking balls and a 33% whiff rate on off-speed pitches. The other interesting statistic for his performance against off-speed pitches is the variance between his expected WOBA (xWBOBA) and actual WOBA. See below for more on these data points.

I don’t want to bore you with definitions, but the data tells us Peña is looking for fastballs and making the most of it when he jumps on them. He does not like either of the other two options but has performed beyond expectations. It’s also interesting to note the current production with fastballs is expected to improve, but he’s par for the course with breaking and off-speed pitches.


Jeremy Peña has come out and provided a spark to an Astros lineup looking to maintain their offensive leverage against opponents. Peña has found power, and it has been very prevalent so far this season. The question to ask ourselves is if there is room to grow? Where is the ceiling for Peña?


Next in the series


Part 2- We will project Jeremy Pena forward. After 30 MLB games we will do the impossible- tell you who we think Jeremy Pena can really be. We will also add a word of warning so be prepared.


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